Flask



FIG. 1 is a front elevational view showing a first embodiment of the new design for a flask;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a left elevational view thereof;

FIG. 4 is a right elevational view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof;

FIG. 7 is a perspective elevational view thereof;

FIG. 8 is a front elevational view showing a second embodiment of the new design for a flask;

FIG. 9 is a rear elevational view thereof;

FIG. 10 is a left elevational view thereof;

FIG. 11 is a right elevational view thereof;

FIG. 12 is a top plan view thereof;

FIG. 13 is a bottom plan view thereof; and,

FIG. 14 is a perspective elevational view thereof. 

CLAIM The ornamental design for a flask, as shown and described. 